Add Easy Rule Name URLs

[JHWelch]

This PR does two related things.

First it allows you to use the PascalCase class name of a rule to find it via the URL. To maintain one consistent canonical URL, this will still redirect to the slug that it is currently. So:
/rule-detail/ArrayToFirstClassCallableRector will 301 redirect to
/rule-detail/array-to-first-class-callable-rector

The second thing this adds is an extra convenient way to find rules, which is resolving them via slug or class name at the root of the URL.

This process also redirects to the /rule-detail/kebab-slug for a canonical URL, but allows for quickly finding a rector rule from name.

So this same rule would be accessible at
https://getrector.com/ArrayToFirstClassCallableRector
and it would redirect to
/rule-detail/array-to-first-class-callable-rector

If you would like either part of this separately without the other I can split this apart, just let me know.

Thanks!

[TomasVotruba]

Looks good, I wanted this feature for such a long time. Thank you 👍